Dr. Sushrut Waikar received his MD degree from Yale University School of Medicine, trained in internal medicine at the University of California, San Francisco, and will join the nephrology faculty at Bigham and Women's Hospital on July 1, 2006. He is currently a candidate for the MPH degree from the Harvard School of Public Health. Mentor: Dr. Gary Curhan is a renowned renal epidemiologist with a long track record of successfully mentoring trainees. Along with a team of leading researchers selected for Dr. Waikar's advisory committee, Dr. Curhan will ensure the success of Dr. Waikar's research training, project, and overall career development. Research: Acute renal failure (ARF) is a common and often devastating complication in hospitalized patients. Despite considerable research efforts to clarify the epidemiology and pathophysiology of ARF, important gaps remain. This proposal aims to contribute to two major areas in ARF research: 1) to address unresolved epidemiologic questions regarding race/ethnicity, sex, and hospital factors that may influence the incidence of and mortality associated with ARF;and 2) to identify novel urinary biomarkers to enable the early identification of acute kidney injury (AKI) and its consequences. For Specific Aim 1 we will use two large databases to investigate the epidemiology of ARF in hospitalized patients: a) the Nationwide Inpatient Sample, the largest all-payer administrative database of hospitalizations in the United States with data on 5 to 8 million admissions annually;and b) the Research Patient Data Registry, a unique database developed at Brigham and Women's Hospital and Massachusetts General Hospital which contains linked administrative, medication, and laboratory data on over 300,000 patients. For Specific Aim 2 we will test four markers of tubular injury in a spectrum of patients at risk of kidney injury. We will test kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase-9 (MMP-9), and N-acetyl-glucosaminidase (NAG) for the ability to identify AKI at least 24 hours prior to a rise in serum creatinine of (= 0.5 mg/dL;we will also test whether urinary biomarkers can identify currently 'sub-clinical'kidney injury, and what independent prognostic information on clinical outcomes may be heralded by urinary biomarker elevations. At the completion of this career development award, Dr. Waikar will have a unique combination of skills and experience that will enable him to succeed as an independent clinical investigator.